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CHAPTER III ALTERNATIVES • irrigation system is lined and because the soils are not of Mancos Shale origin. The Orchard Mesa Power Canal and laterals were excluded because most of them are lined and their location adjacent to the Colorado River prevents seepage from irrigation systems from picking up significant amounts of salt before reentering the river. Three points emphasized in the authorizing legislation for the Grand Valley Unit were important considerations in Stage Two planning. This language, in Section 202 of Public Law 93-320, states that (1) measures are to include lining canals and laterals; (2) where possible, the canals and laterals are to be consolidated into fewer and more efficient facil- ities; and (3) the Secretary, before starting construction of the Grand Valley Unit features, shall enter into operation and maintenance con- tracts with agencies or individuals owning, operating, and maintaining the distribution systems. Most of the laterals in the Grand Valley are privately owned. Under a grant from Reclamation, the Colorado Water Conservation Board of the State of Colorado has assumed the responsibility for- establishing the entities that will organize the lateral groups. Major water supply en- tities, including the Grand Valley Irrigation Company and Che Palisade, Orchard Mesa, and Mesa County Irrigation Districts, have indicated to the Colorado Water Conservation Board their intent to be the entities which would operate and maintain the private laterals in their respective areas. The Colorado Water Conservation Board and the entities will be studying the legal and accounting implications of their participation in the lateral improvement program. Salinity control measures other than lining were considered in Stage Two studies to determine if more cost-effective control measures existed. This led to Reclamation considering a variety of conceptual methods for salinity control, including various types of canal and lateral improve- ments, pipe installation, soil sealants, combining canal systems, col- lecting and disposing of saline water, and industrial uses of saline water. Each alternative studied included several distinct increments which could be constructed independent of other increments. Each increment was planned to be a logical and practical part of the delivery system, such as an entire lateral system or a major unbroken segment of canal, or both. Each increment was also planned to be large enough to accommodate modern construction equipment and practices, to provide for continuity and ease of operation and maintenance, and to allow salt loading values to be attributed to the increment. The application of the four tests of viability identified two viable alternatives (alternatives A and B) which were studied in greater detail. The interest rate (5 5/8 percent) used for Stage Two studies was the planning rate in effect in 1974 when the Grand Valley Unit was au- thorized for construction. Analyses were performed based on January 1984 appraisal-level prices, a level sufficient to provide an adequate base for evaluating alternatives. 17